Study On The Application Of Endogenous Water Molecular Diffusion And Exogenous Gd-DTPA Contrast Agent Tracing In Brain Tumors

Part I Study of pathological types and cell proliferation of meningioma based on non-Gaussian distribution of high b value water molecule diffusion(DKI)Purpose To explore the differential diagnostic value of endogenous water molecule diffusion imaging(i.e.,diffusion kurtosis imaging,DKI)in meningiomas and to assess the degree of cell proliferation.Methods For this study,we retrospectively enrolled 35 patients of cerebral meningioma with DKI which included axial diffusion coefficient(AD),radial diffusion coefficient(RD),mean diffusion coefficient(MD),fractional anisotropy(FA),axial kurtosis(AK),radial kurtosis(RK)and mean kurtosis(MK).All of these metrics were normalized according to contralateral normal-appearing white matter(NAWMc).Patients were divided into two groups(benign and malignant meningioma)and were further analyzed using the indeperndent sample t test and receiver operating characteristic(ROC)curve.A one-way ANOVA analysis was used to analyze four groups divided according to pathological subtypes.Results The metrics of AD,normalized AD,normalized MD,MK and normalized MK showed a significant difference between benign and malignant group,and MK showed relatively higher diagnostic ability with its cut-off value,area under the curve(AUC),sensitivity and specificity of 0.875,0.780,70%and 89%,respectively.The metrics of normalized MD,RD and normalized RD,FA and normalized FA,AK and normalized AK,and RK showed significant difference among four subtypes.MK and RK in meningioma were found to correlate positively with the Ki-67 labeling index(Ki-67 LI).Conclusions DKI metrics can effectively differentiate benign and malignant meningiomas and different subtypes of meningiomas.In addition,DKI metrics may potentially reflect the cell proliferation of tumor tissues.Part ? Application of histogram analysis of IVIM and DCE-MRI parameters in brain tumorsPurpose To assessment the differential diagnostic capabilities of endogenous water molecule diffusion(i.e.,intravoxel incoherent motion,IVIM)and exogenous Gd-DTPA contrast agent tracer imaging(i.e.,dynamic contrast enhancement,DCE)parameters for different grades of gliomas by histogram analysis and to explore the correlation between these parameters.Methods Thirty-nine patients with glioma underwent IVIM and DCE-MRI imaging at 3.0T.Quantitative parameters(mean,median,10th,25th,75th and 90th percentiles)from IVIM(ADC,D,D*,f,and their product fD*)and DCE-MRI(Ve,Vp,Ktrans,and Kep)were analyzed.The independent Student's t-test and Mann-Whitney U-tests were used to assess whether these parameters could distinguish low-from high-grade glioma.Receiver-operating characteristic(ROC)curve analysis was performed to determine and compare diagnostic efficiency of IVIM and DCE-MRI parameters in differentiating low-and high-grade gliomas based on the area under ROC curve(AUC).Results Various histogram statistics of ADC,D,D*,Ve,and Vp can be used to differentiate between low-grade and high-grade glioma,and between grade ?,?,and ? glioma.ROC analysis showed that diffusion parameters ADC and D generally yielded larger AUC values than DCE parameters Ve,and Vp.However,differences in AUC values of these parameters did not reach statistical significance.Both ADC and D were negatively correlated with Vp,D*was weakly correlated with Ktrans and Ve,and positively correlated with Vp.The JD*had a moderate positive correlation with Ktrans,Ve,and Vp,respectively.Conclusions Both IVIM and DCE parameters can be used for preoperative grading of gliomas.There was a certain correlation between IVIM and DCE parameters.Part ? The optimal b value of DWI in the evaluation of brain tumorsPurpose To evaluate the differential diagnostic value of ADC values fitted with different b-value combinations in benign and malignant meningiomas,and to investigate the optimal b value of DWI imaging in differential diagnosis of meningiomas.Methods Thirty-six cases of meningioma were eventually included in the experiment.According to the pathological results,they were divided into two groups:benign and malignant meningioma.ADC values fitted by 11 b values(0,50,100,150,200,300,400,500,700,900,1000 s/mm2)and any pairs of two b values(56 pairs in total)were used to distinguish between benign and malignant meningioma.Independent sample t-test and Mann-Whitney U test were used to evaluate the differential diagnostic value of ADC values,and receiver operating characteristic(ROC)curves were used to determine the diagnostic performance,thresholds,sensitivity,and specificity of ADC values.Results The ADC values of benign malignant,and all meningiomas showed a decreasing trend with the increase of b value,and the smaller the b value,the greater the decrease.When the b value was ? 200 s/mm2,any combinations of b values could discriminate between benign and malignant meningioma(all P values<0.05).The ADC values obtained by fitting b = 700 and b = 1000 s/mm2 had the highest AUC value(0.785),and the threshold,sensitivity and specificity for distinguishing between benign and malignant meningiomas were 0.755×10-3 mm2/s,72.0%,and 72.7%,respectively.The difference between b = 900 s/mm2 and any other b-values(including 200,300,400,500,700,and 1000 s/mm2)in benign and malignant meningiomas was statistically significant(P = 0.022,0.010,0.015,0.004,0.018,and 0.026,respectively).Conclusions ADC values of DWI obtained by fitting different combinations of b-values can effectively distinguish between benign and malignant meningiomas.The ADC values of benign,malignant,and all meningioma showed a decreasing trend with the increase of b value,and the smaller the b value,the greater the decrease,b-700 and 1000 s/mm2 is considered to be the most significant b value.